1. Field of the Invention
The present invention relates to wireless communications and, more particularly, to methods and systems of providing call services in a cellular communication system.
2. Description of Related Art
Cellular wireless is an increasingly popular means of personal communication in the modem world. People are using cellular wireless networks for the exchange of voice and data over cellular telephones, Personal Digital Assistants (PDAs), wirelessly equipped computers, and other devices. In principle, a user can seek information over the Internet or call anyone over the Public Switched Telephone Network (PSTN) from any place inside the coverage area of the cellular wireless network.
In a typical cellular wireless system, a coverage area is divided geographically into a number of cell sites or cells, each defined by an RF radiation pattern from a respective base transceiver station (BTS) antenna. The BTS antennae in the cells are in turn coupled to a base station controller (BSC), which is then coupled to a switch, such as a mobile switching center (MSC). The MSC may then be coupled to a telecommunications network such as the PSTN and/or the Internet.
When a wireless communication device (WCD) is positioned in a cell, the WCD communicates via an RF air interface with the BTS antenna of the cell. Consequently, a communication can be established between the WCD and other entity on the wireless network or the telecommunications network, via the air interface, the BTS, the BSC and the switch. Such a communication may be referred to as a “call”, whether the communication is a traditional voice call or a more advanced data session. To further distinguish between the two, a data session is typically referred to as a data call.
Cellular wireless architecture has also been adopted to deploy fixed wireless local loop (WLL) networks that utilize wireless access methods in place of traditional fixed wireline links to deliver voice and data communications (e.g. telephone and Internet services) to telecommunications users at their residential homes and business offices, for instance. WLL devices usually stay in a relatively fixed location and often connect to AC current rather being battery-powered to support mobility (as in the case of portable cellular telephones, for instance).
For example, a WLL device may be in the form of a fixed WLL hub (or terminal) with wireless capabilities that can be installed within the premises of a residential building or an office building to interconnect traditional wireline terminals, such as a landline telephone, a fax machine, and/or a computer modem, to a wireless network (via a BTS, BSC, and a MSC) using a suitable communication protocol, typically a Code Division Multiple Access (CDMA) protocol. A WLL device can also be a stand-alone WLL phone, or even a WLL payphone, that directly interconnects a user to the wireless network. The wireless network then interfaces with a telecommunications network, such as the PSTN, to enable the WLL device to communicate with other communication terminals, such as by placing and receiving calls.
Early cellular communication systems provided only basic functions associated with call processing, such as simply setting up and disconnecting calls. Today's cellular systems, however, provide a wide array of supplementary services and advanced wireless features made available to wireless users. In general, enhanced or special call services encompass those call features that do more than simply place or terminate telephone calls as dialed.
For example, a user may subscribe to call forwarding service, in which calls directed to the user's WCD device may be forwarded to another phone line. In another example, a three-way calling feature allows a mobile subscriber currently engaged in a two-way call to add in a third party, so that all parties may communicate directly. In yet another example, when a WCD is currently engaged in a call, a call waiting service provides for alerting a user when another call is placed to the WCD. According to the service, a wireless network may send an audible in-band tone over a traffic channel assigned to the WCD for communicating call traffic, thus alerting the user of another incoming call. The user can then connect to the new incoming call by pressing a designated key on the device and can toggle between the two calls if so desired.
Further, many of the services for which a subscriber or group of subscribers is authorized can be turned on and off (i.e., activated and deactivated) or modified. For instance, a subscriber may subscribe to a voice mail service, which directs unanswered calls to voice mail (a type of call forwarding), and the subscriber may be given the ability to turn this service on or off. As another example, the subscriber may be given the ability to set and/or modify the number to which calls to the subscriber should be forwarded.
Although a variety of services currently made available to wireless communications users provide many convenient functions for handling calls, services offering new features are still in demand.